Multi-chassis switch having a modular center stage chassis

ABSTRACT

A system may comprise a first group of switches, each switch including a first group of inputs and outputs, and a first group of controllers, each controller being independent from one another and corresponding to a switch of the first group of switches, to selectively control the switch to connect the switch&#39;s inputs with outputs. The first group of switches and controllers may be installed in a chassis. The system may comprise a second group of switches, each switch including a second group of inputs and outputs, and a second group of controllers, each controller corresponding to a switch of the second group of switches, to selectively control the switch to connect the switch&#39;s inputs with outputs. The second group of controllers may control and connect, via a group of control links, to the first group of controllers.

BACKGROUND

A switch facilitates direct communication between network devices,connected to the switch's ports, by interconnecting the ports through aswitch fabric. The switch fabric may include three stages: an ingressstage, an egress stage, and a center stage. Each stage may include oneor more crossbar switches, hereinafter referred to as crossbars.Information may enter the switch fabric via an ingress stage crossbar,and may be routed, via one or more center stage crossbars, to anappropriate egress stage crossbar.

SUMMARY

According to some possible implementations, a system may comprise afirst device associated with an ingress stage and an egress stage of aswitch fabric. The first device may include a first crossbar which isassociated with the switch fabric. The first device may comprise a firstcrossbar component, associated with the ingress stage, and a secondcrossbar component, associated with the egress stage. The system mayfurther include a second device associated with a center stage of theswitch fabric. The second device may include a second crossbar,associated with the switch fabric. The second crossbar may comprise athird crossbar component, associated with the center stage. The seconddevice may further comprise a third crossbar, associated with the switchfabric. The third crossbar may comprise a fourth crossbar componentassociated with the center stage. The third crossbar component mayconnect, via one or more data links, to the first crossbar component andto the second crossbar component but not to the third crossbar. Thefourth crossbar component may connect, via the one or more data links,to the first crossbar component and to the second crossbar component butnot to the second crossbar. The system may comprise a first controllerconnecting, via one or more control links, to the first crossbar. Thesystem may comprise a second controller connecting, via the one or morecontrol links, to the second crossbar and to the first controller butnot to the third crossbar. The system may comprise a third controllerconnecting, via the one or more control links, to the third crossbar andto the first controller but not to the second crossbar.

According to some possible implementations, a system may comprises afirst switching component, installed in a first chassis, to receive datafrom a sending device. The data may be intended for a receiving device.The system may comprise a first controller, installed in the firstchassis, to obtain first control information, associated with forwardingthe data; identify, based on the first control information, a secondswitching component, installed in a second chassis, and a thirdswitching component, installed in a third chassis; and control the firstswitching component to provide a first portion of the data, provided bythe sending device, to the second switching component and a secondportion of the data, provided by the sending device, to the thirdswitching component. The system may comprise a second controller,separate from the first controller, to obtain, from a master controller,second control information associated with forwarding the data;identify, based on the second control information, a fourth switchingcomponent, not installed in the second chassis, connected to thereceiving device; and control, based on the second control information,the second switching component to forward the first portion of the datato the fourth switching device. The system may comprise a thirdcontroller, separate from the first controller and independent of thesecond controller, to obtain, from a master controller, third controlinformation associated with forwarding the data; identify, based on thethird control information, the fourth switching component, not installedin the third chassis, connected to the receiving device; and control,based on the third control information, the third switching component toforward the second portion of the data to the fourth switching device.

According to some possible implementations, a system may comprise achassis and a first group of switches installed within the chassis. Eachswitch, of the first group of switches, may include a first group ofinputs and a first group of outputs. The system may comprise a firstgroup of controllers, associated with the first group of switches,installed within the chassis. Each controller, of the first group ofcontrollers, may be independent of any other controller, of the firstgroup of controllers, and may correspond to a switch, of the first groupof switches, to selectively control the switch to connect inputs, of thefirst group of inputs, with outputs, of the first group of outputs. Thesystem may comprise a second group of switches, including a second groupof inputs and a second group of outputs. The first group of inputs mayconnect, via a group of data links, to the second group of outputs, andthe first group of outputs may connect, via the group of data links, tothe second group of inputs. The system may comprise a second group ofcontrollers, associated with the second group of switches, to controlthe second group of switches to selectively connect inputs, of thesecond group of inputs, to outputs, of the second group of outputs. Thesecond group of controllers may control the first group of controllers.The second group of controllers may connect, via a group of controllinks, to the first group of controllers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C are diagrams of overviews of example implementationsdescribed herein;

FIG. 2 is a diagram of an example implementation of a multi-chassisnetwork switch having a modular center stage device;

FIG. 3 is a flow chart of an example process for forwarding data using amulti-chassis network switch having one or more independent modularcenter stage devices;

FIGS. 4A-4G are diagrams of an example implementation relating to theexample process shown in FIG. 3; and

FIGS. 5A-5D are diagrams of example implementations relating to theexample process shown in FIG. 3.

DETAILED DESCRIPTION

The following detailed description of example implementations refers tothe accompanying drawings. The same reference numbers in differentdrawings may identify the same or similar elements.

A network switch facilitates efficient, directed communication betweendevices connected to the switch's ports by interconnecting the portswith a dynamically configurable switching fabric. The switch fabric mayhave three stages: an ingress stage for receiving data from ports, anegress stage for forwarding the received data to ports, and a centerstage for interconnecting the ingress stage to the egress stage. Theingress and egress stages may include ingress and egress crossbars fordynamically connecting ingress and egress ports, respectively, to one ormore center stage crossbars. Each center stage crossbar may represent adata plane of the switch fabric, enabling a connection between aparticular ingress port and a particular egress port. For example, thecrossbars of the switch fabric may form a Clos network in someimplementations.

The quantity of data planes of a switch's center stage determines, inpart, the switch's bandwidth, while the ratio of data planes to portsdetermines the switch's blocking characteristics (i.e., the extent towhich any available ingress port may be connected to any availableegress port). Thus, increasing the quantity of center stage crossbarsmay improve the performance of the switch and/or may maintain theswitch's performance when adding new ports. However, physicalconstraints, such as the capacity of an equipment rack, dimensions of aroom, output of a power supply, performance of a cooling system, or thelike, may limit the quantity of center stage crossbars which may beprovided within a single chassis. Further, a network operator may havebandwidth and/or port quantity requirements that change over time. Thus,a fixed capacity center stage chassis may complicate and/or increase thecost and network downtime associated with the addition, removal, and/orreplacement of center stage crossbars.

Implementing the center stage as a group of one or more independentcenter stage devices may provide a network operator with a multi-chassisnetwork switch that is simple to implement and scalable while satisfyingvarious physical constraints. Further, a center stage implemented usingindependent center stage devices does not present a single point offailure for the switch, thereby allowing the switch to continueoperating despite a failure of one or more center stage devices.

FIGS. 1A-1C are diagrams of overviews of example implementations 100-120described herein.

As shown in FIG. 1A, assume, for example implementation 100, that afirst switch includes: two equipment racks, each containing an outerstage device, at respective first and second locations; and anotherequipment rack, containing a center stage device, at a third location.Assume further that each of the outer stage devices connects, via datalinks, to the center stage device, to form a switch fabric forforwarding data to and/or from ports of the outer stage devices, andthat all the devices interconnect, via control links, for exchangingcontrol information associated with configuring the switch fabric.

Assume, for example implementation 100, that a second switch alsoincludes outer stage devices located within equipment racks at first andsecond locations. Assume further that a center stage of the secondswitch includes a group of independent modular center stage devicesapportioned between the equipment racks at the first and secondlocations. Thus, the use of modular center stage devices may allow thesecond switch to occupy less physical space than the first switch whileproviding the same performance. Further, in case of a failure of one ormore modular center stage devices, the second switch may continueoperating, albeit at reduced capacity, redundancy, and/or bandwidth,whereas a failure of the center stage chassis of the first switch mayrender the first switch inoperable.

As shown in FIG. 1B, assume, for example implementation 110, that athird switch also includes outer stage devices located within equipmentracks at first and second locations. Assume further that the centerstage of the third switch includes a group of independent modular centerstage devices apportioned between two other equipment racks, physicallyand/or geographically separate from the equipment racks at the first andsecond locations. Thus, the use of modular center stage devices allowsthe third switch to implement a center stage which may be provided indifferent locations while providing the same performance as the firstmulti-chassis network switch. Thus, implementing the third switch mayallow a network operator to operate a network when, e.g., particularphysical limitations make providing a center stage device in a singlelocation difficult or unfeasible and/or when physical and/orgeographical diversity of data links may be desirable (e.g., for linkprotection). Like the second switch, the third switch may continueoperating, albeit at reduced capacity, redundancy, and/or bandwidth,despite the failure of a modular center stage device.

As shown in FIG. 1C, assume, for example implementation 120, that afourth switch also includes outer stage devices located within equipmentracks at first and second locations. Assume further that the centerstage of the third switch includes a first group of independent modularcenter stage devices apportioned between the equipment racks at thefirst and second locations and a second group of independent modularcenter stage devices apportioned between two other equipment racks,physically and/or geographically separate from the equipment racks atthe first and second locations. For example, a network operator mayinitially implement only the first group of independent modular centerstage devices (e.g., based on initial budget and/or performancerequirements), resulting in the second switch shown in FIG. 1A, and maylater implement the second group of independent modular center stagedevices, and associated data/control links (e.g., based on subsequentbudget and/or performance requirements). Alternatively, the networkoperator may initially implement only the second group of independentmodular center stage devices, resulting in the third switch as shown inFIG. 1B, and may later implement the first group of independent modularcenter stage devices, and associated data/control links. Thus,implementing a switch using independent modular center stage devices mayallow a network operator to modify and/or upgrade a switch, withinparticular physical and/or budgetary constraints, to improveperformance, resilience, or the like without network downtime.

In this way, a network operator may use one or more independent modularcenter stage devices to implement a scalable, resilient multi-chassisnetwork switch within particular physical constraints.

FIG. 2 is a diagram of an example implementation of a multi-chassisnetwork switch 200 having a modular center stage device. As shown inFIG. 2, switch 200 may forward data between network devices 210 and mayinclude a group of outer stage devices 220-1, . . . , 220-R (R≧1)(hereinafter referred to collectively as outer stage devices 220, andindividually as outer stage device 220) and a group of center stagedevices 230-1, . . . , 230-L (L≧1) (hereinafter referred to collectivelyas center stage devices 230, and individually as center stage device230). In some implementations, each outer stage device 220 and/or eachcenter stage device 230 may include a separate chassis for housingcomponents thereof (e.g., sized to fit in a particular physical space,such as within a communications rack, and/or sized to fit a particularquantity of components). In some implementations, outer stage devices220 may be connected to each other and/or to center stage devices 230via links 240 for transferring data and/or control information. In someimplementations, center stage devices 230 may operate independently fromeach other without being connected to each other via links 240 fortransferring data and/or control information. Links 240 may includewired connections (e.g., copper wire, optical fiber, or the like),wireless connections (e.g., radio signals, optical signals, or thelike), or a combination of wired and wireless connections fortransferring data and/or control information between devices.

Network device 210 may include a device capable of receiving,transmitting, processing, routing, etc. information (e.g., datapackets). For example, network device 210 may include a line cardchassis (LCC), a router, a switch, a gateway, a modem, a firewall, anetwork interface connection (NIC), a hub, a bridge, an optical add-dropmultiplexer (OADM), or another type of network device. In someimplementations, network device 210 may include one or more input portsassociated with receiving packets and one or more output portsassociated with transmitting packets. In some implementations, networkdevice 210 may be connected (e.g., via one or more links 240) to switch200 via an outer stage device 220 to send data, via switch 200, toanother network device 210. In some implementations, network device 210may send and/or receive control information to/from one or more devicesof switch 200 (e.g., via one or more links 240).

Outer stage device 220 may include a device capable of receiving,storing, transmitting, processing, routing, etc. information (e.g.,packets containing data and/or control information) associated withswitch 200. For example, outer stage device 220 may include a LCC, arouter, a switch, a gateway, a firewall, a bridge, or another type ofnetwork device. In some implementations, outer stage device 220 mayinclude a group of one or more ports 222 (hereinafter referred tocollectively as ports 222, and individually as port 222), a portcontroller 224, an outer stage crossbar 226, and a crossbar controller228.

Ports 222 may receive and/or transmit packets (e.g., from and/or to oneor more network devices 210). For example, ports 222 may include one ormore input ports associated with receiving packets (e.g., from one ormore network devices 210) and one or more output ports associated withtransmitting packets (e.g., to one or more network devices 210).

Port controller 224 may include a component or collection of components,connected to crossbar controller 228 and ports 222, to receive incomingpackets, to process incoming and/or outgoing packets, and/or to transmitoutgoing packets. For example, port controller 224 may include ports(e.g., corresponding to, and/or integrated with, ports 222), an Ethernetinterface, and/or another type of interface, a central processing unit(CPU), and/or a memory device. Port controller 224 may include packetprocessing component(s), switch interface component(s), Internetprocessor component(s), memory device(s), or the like. Port controller224 may also represent a separate switch.

Port controller 224 may perform certain operations on incoming and/oroutgoing packets, such as decapsulation, encapsulation, demultiplexing,multiplexing, queuing, dequeuing, etc., which may facilitate theprocessing and/or transportation of incoming and/or outgoing packets.Port controller 224 may receive incoming packets (e.g., via ports 222)and may forward the incoming packets to other port controllers 224(e.g., via outer stage crossbar 226). For example, port controller 224may receive incoming packets and may determine (e.g., based on controlinformation received from crossbar controller 228) operations to performand/or other port controllers 224 to which the incoming packets may besent.

Port controller 224 may perform incoming packet buffering operations.For example, port controller 224 may receive packets and may removeheader information from the packet. Port controller 224 may perform asegmentation operation on the packet data (e.g., on the data payloadportion of the packet) by breaking the packet data into fixed-lengthfragments (herein, referred to collectively as “data units” andindividually as a “data unit”). Port controller 224 may generate controlblocks to store packet control information associated with the dataunits. Port controller 224 may store the data units in a data memory andmay store the control blocks in a control memory. Alternatively, oradditionally, port controller 224 may send the control blocks tocrossbar controller 228.

Port controller 224 may perform outgoing packet buffering operations.For example, port controller 224 may retrieve control blocks fromcontrol memory and may remove control protection information from thecontrol blocks (e.g., checksum information and/or other forms of controlprotection information). From the control protection information, portcontroller 224 may perform a data integrity operation to determinewhether the packet control information, obtained from the controlblocks, contains an error. Port controller 224 may, based on the packetcontrol information, retrieve data units from data memory and mayreorder/reassemble the data units into outgoing packets for transmissionto another outer stage device 220 and/or a network device 210. Portcontroller 224 may communicate with another port controller 224 by,e.g., sending control information (e.g., control blocks) to crossbarcontroller 228, which may forward the control information to the anotherport controller 240 (e.g., via another crossbar controller 228interconnected by links 240). Additionally, or alternatively, portcontroller 224 may communicate with another port controller 224 bysending data units to outer stage crossbar 226, which may forward thedata units to the other port controller 240 (e.g., via a center stagedevice 230 interconnected via links 240).

Outer stage crossbar 226 may include an ingress stage crossbar componentand an egress stage crossbar component. The ingress stage crossbarcomponents of the outer stage crossbars 226 of the outer stage devices220 may, together, act as an ingress stage of a switch fabric of switch200. The ingress stage crossbar component of outer stage crossbar 226may include input cross-points connected (e.g., via links 240) to ports222, output cross-points connected (e.g., via links 240) to one or morecenter stage crossbars 232, and a controllable switching device tointerconnect particular input cross-point(s) with particular outputcross-point(s). The ingress stage crossbar component may, thus, beconfigured (e.g., by crossbar controller 228) to receive packets fromingress ports 222 and provide the packets to the one or more centerstage crossbars 232.

Likewise, the egress stage crossbar components of the outer stagecrossbars 226 of the outer stage devices 220 may, together, act as anegress stage of the switch fabric of switch 200. The egress stagecrossbar component of outer stage crossbar 226 may include inputcross-points connected (e.g., via links 240) to one or more center stagecrossbars 232, output cross-points connected (e.g., via links 240) toports 222, and a controllable switching device to interconnectparticular input cross-point(s) with particular output cross-point(s).The egress stage crossbar component may, thus, be configured (e.g., bycrossbar controller 228) to receive packets from the one or more centerstage crossbars 232 and provide the packets to egress ports 222.

Crossbar controller 228 may include a processor, a microprocessor, someform of hardware component (e.g., an application specific integratedcircuit (ASIC) or a field programmable gate array (FPGA)), or a similartype of processing component. In some implementations, for example,crossbar controller 228 may include a memory component, such as a randomaccess memory (RAM), a read only memory (ROM), content-addressablememory (CAM), and/or another type of dynamic or static storage device(e.g., a flash memory, a magnetic memory, an optical memory, etc.) thatstores information and/or instructions. In some implementations, forexample, crossbar controller 228 may include a storage component, suchas a hard disk (e.g., a magnetic disk, an optical disk, a magneto-opticdisk, a solid state disk, etc.), a compact disc (CD), a digitalversatile disc (DVD), a floppy disk, a cartridge, a magnetic tape,and/or another type of computer-readable medium, along with acorresponding drive. In some implementations, for example, crossbarcontroller 228 may include an Ethernet controller and/or anothercontroller component. Crossbar controller 228 may perform high-levelmanagement functions for switch 200. For example, crossbar controller228 may communicate with other networks and/or systems connected toswitch 200 to exchange control information regarding network topology(e.g., to detect the addition, removal, and/or failure of a networkdevice 210, an outer stage device 220, a center stage device 230, a link240, and/or a component thereof).

Crossbar controller 228 may create, based on the control information,and/or maintain, in memory associated with crossbar controller 228, arouting table and/or forwarding table(s). Crossbar controller 228 maysend and/or receive (e.g., via one or more links 240) controlinformation to/from port controller 224, another crossbar controller228, and/or a crossbar controller 234 of a center stage device 230.Crossbar controller 228 may control outer stage crossbar 226 to senddata to one or more center stage crossbars 232 via an ingress stagecrossbar component of outer stage crossbar 226 and/or to receive datafrom one or more center stage crossbars 232 via an egress stage crossbarcomponent of outer stage crossbar 226. Crossbar controller 228 may alsoperform other general control and monitoring functions for switch 200.For example, crossbar controllers 228, associated with switch 200, mayselect a particular crossbar controller 228 to act as a master crossbarcontroller 228 to centralize control functions of switch 200.Alternatively, or additionally, multiple crossbar controllers 228 mayact, together or separately, as master crossbar controllers (e.g.,control functions may be shared and/or duplicated among controllers).For example, each crossbar controller 228 of switch 200 maycontinuously, periodically, and/or occasionally broadcast controlinformation to the other crossbar controllers 228 of switch 200 (e.g.,using a switch and/or hub associated with a control plane of switch200).

Center stage device 230 may include a device capable of receiving,storing, transmitting, processing, routing, etc. information (e.g.,packets containing data and/or control information) associated with acenter stage of a switch fabric of switch 200. In some implementations,center stage device 230 may include a group of one or more center stagecrossbars 232-1, . . . , 232-M (M≧1) (hereinafter referred tocollectively as center stage crossbars 232, and individually as centerstage crossbars 232) and a corresponding group of one or more crossbarcontrollers 234-1, . . . , 234-M (hereinafter referred to collectivelyas crossbar controllers 234, and individually as crossbar controller234). For example, a subset of the group of center stage crossbars 232may be integrated with a corresponding subset of the group of crossbarcontrollers 234 to form a fabric card, and center stage device 230 mayinclude a group of fabric cards installed in a modular chassis.

Center stage crossbar 232 may include a center stage crossbar component.The center stage crossbar components of the center stage crossbars 232of the center stage devices 230 may, together, act as a center stage ofa switch fabric of switch 200 and may be configured (e.g., by crossbarcontroller 234) to receive packets from an ingress stage of one or moreouter stage crossbars 226 and provide the packets to an egress stage ofone or more outer stage crossbars 226.

The center stage crossbar component may include input cross-points andoutput cross-points, connected to one or more outer stage crossbars 226(e.g., via links 240), and a controllable switching device tointerconnect particular input cross-point(s) with particular outputcross-point(s). A quantity of input and/or output cross-points may bedetermined based on a maximum expected quantity of outer stage devices220 (e.g., R in FIG. 2). For example, the quantity of input and/oroutput cross-points may be equal to, or greater than, the maximumexpected quantity of outer stage devices 220 such that each center stagecrossbar 232 may be connected to, and therefore provide a data planefor, each outer stage device 220. Alternatively, the quantity of inputand/or output cross-points may be fewer than the maximum expectedquantity of outer stage devices 220 such that, for a quantity of outerstage devices 220 greater than the quantity of input and/or outputcross-points, each center stage crossbar 232 may provide a data planefor only a subset of the outer stage devices 220. Center stage crossbars232 having insufficient input and/or output cross-points to connect toevery outer stage device 220 may be interconnected (e.g., via links 240)to form a multi-staged crossbar switch, and/or the quantity of outerstage devices 220 to be connected to center stage crossbar 232 may bereduced by splitting switch 200 into two switches 200.

Crossbar controller 234 may include a processor, a microprocessor, someform of hardware component (e.g., an ASIC or an FPGA), or a similar typeof processing component. In some implementations, for example, crossbarcontroller 234 may include a memory component (e.g., one or more of aRAM, a ROM, a CAM, a flash memory, a magnetic memory, an optical memory,or the like) and/or a storage component (e.g., one or more of a harddisk, a CD, a DVD, a floppy disk, a cartridge, a magnetic tape, and/oranother type of computer-readable medium, along with a correspondingdrive) that stores information and/or instructions. In someimplementations, for example, crossbar controller 234 may include anEthernet controller and/or another controller component. Crossbarcontroller 234 may communicate with a crossbar controller 228 (e.g., amaster crossbar controller 228) to exchange control informationregarding network topology (e.g., to detect the addition, removal,and/or failure of a network device 210, an outer stage device 220, acenter stage device 230, a link 240, and/or a component thereof).Crossbar controller 234 may receive and/or maintain, in memoryassociated with crossbar controller 234, a routing table and/orforwarding table(s) associated with forwarding data between outer stagedevices 220. Crossbar controller 234 may send and/or receive (e.g., viaone or more links 240) control information to/from the master crossbarcontroller 234. Crossbar controller 234 may control center stagecrossbar 232 to forward information received from an outer stagecrossbar 226 to one or more outer stage crossbars 226. Each crossbarcontroller 234 may operate independently from other crossbar controllers234.

The number and arrangement of devices and connections shown in FIG. 2are provided as an example. In practice, there may be additional devicesand/or connections, fewer devices and/or connections, different devicesand/or connections, or differently arranged devices and/or connectionsthan those shown in FIG. 2. Furthermore, two or more devices shown inFIG. 2 may be implemented within a single device, or a single deviceshown in FIG. 2 may be implemented as multiple, distributed devices.Additionally, or alternatively, a set of devices (e.g., one or moredevices) of switch 200 may perform one or more functions described asbeing performed by another set of devices of switch 200.

FIG. 3 is a flow chart of an example process 300 for forwarding datausing a multi-chassis network switch having one or more independentmodular center stage devices. In some implementations, one or moreprocess blocks of FIG. 3 may be performed by devices of switch 200(e.g., outer stage device 220 and/or center stage device 230). In someimplementations, one or more process blocks of FIG. 3 may be performedby another device or a group of devices separate from or includingswitch 200 (e.g., a network device 210).

As shown in FIG. 3, process 300 may include receiving, from a sendingnetwork device, data, to be forwarded to a receiving network device, viaa port of a sending outer stage device (block 310). For example, asending network device 210 may provide, via link(s) 240, data (e.g., asa packet) to an ingress port 222 of an outer stage device 220 associatedwith a switch 200. Outer stage device 220 may likewise receive the datafrom sending network device 210 via ingress port 222. The data mayinclude a payload and/or control information associated with forwardingthe data to one or more recipients. In this way, switch 200 may receive,via port(s) 222 of outer stage device(s) 220, data to be forwardedbetween network device(s) 210.

As further shown in FIG. 3, process 300 may include providing, from thesending outer stage device, control information, associated withforwarding data, to a master controller (block 320). For example, a portcontroller 224 associated with ingress port 222 may identify, from datareceived by ingress port 222, and/or determine, based on receiving thedata, control information associated with forwarding the data. Thecontrol information may identify sending network device 210, one or morerecipient devices, ingress port 222, one or more links 240, a sendingdate/time, or the like. Port controller 224 may provide, via link(s)240, the control information to a crossbar controller 228 associatedwith outer stage device 220. In some implementations, the controlinformation may include information associated with a functionality(e.g., a power state, an offline/online status, an error state, or thelike) and/or a connectivity of port(s) 222. Crossbar controller 228 maylikewise receive the control information from port controller 224.Crossbar controller 228 may process (e.g., along with previouslyreceived control information) and/or store the control information in arouting table, in one or more forwarding table(s), as afunctionality/connectivity status of devices of switch 200, or the like.

In some implementations, crossbar controller 228 of outer stage device220 may act as a master controller for switch 200 by maintainingreference control information for other devices of switch 200 and/or bycontrolling other devices of switch 200 (e.g., center stage device(s)230 and/or other outer stage devices 220).

In some implementations, another controller or group of controllers(e.g., another crossbar controller 228 and/or a controller of a networkdevice 210) may act as a master controller of switch 200. Crossbarcontroller 228 may likewise act as a slave controller for switch 200.For example, crossbar controller 228 may provide, via link(s) 240,control information, associated with and/or stored by outer stage device220, to the master controller. In some implementations, crossbarcontroller 228 of outer stage device 220 may provide, as controlinformation to the master controller, information associated with afunctionality (e.g., a power state, an offline/online status, an errorstate, or the like) and/or a connectivity of outer stage device 220 toenable the master controller to identify outer stage device 220'sassociation with switch 200 and/or connectivity to center stagedevice(s) 230 and/or to other outer stage devices 220. In this way, themaster controller may identify outer stage device(s) 220 which formingress and egress stages of switch 200's switch fabric and port(s) 222,of outer stage device(s) 220, by which network device(s) 210, for whomdata is to be forwarded, connect to switch 200.

As further shown in FIG. 3, process 300 may include obtaining, by themaster controller, control information associated with identifyingavailable center stage devices (block 330). For example, the mastercontroller may receive control information, via link(s) 240, from centerstage device(s) 230 of switch 200, from outer stage device(s) 220connected to the center stage device(s) 230, and/or from another device(e.g., a network device 210). The control information may identify thecenter stage device(s) 230 of switch 200, center stage crossbar(s) 232of the center stage device(s) 230, and/or links 240 connecting thecenter stage device(s) 230 and/or center stage crossbar(s) 232 withouter stage device(s) 220. The master controller may receive controlinformation based on sending, via link(s) 240, a request to anotherdevice (e.g., to center stage device(s) 230 and/or to outer stagedevice(s) 220 connected thereto).

Alternatively, or additionally, the master controller may receivecontrol information based on the satisfaction of a threshold condition(e.g., based on a schedule, a connection/disconnection of a device ofswitch 200, or the like). For example, center stage device 230 mayprovide control information upon connecting to other devices of switch200 (e.g., as a broadcast) and/or outer stage device 220 may providecontrol information upon detecting the connection and/or disconnectionof a center stage device 230 (e.g., based on a status of one or morelink(s) 240 between outer stage device 220 and center stage device 230,detection of an error associated with outer stage device 220 forwardingdata via center stage device 230, or the like).

Additionally, or alternatively, the master controller may generatecontrol information based on performing an operation to identify centerstage device(s) 230 of switch 200 (e.g., based on receiving a responseto a request provided to link(s) 240 associated with center stagecrossbar(s) 232 and/or crossbar controller(s) 234 associated with thecenter stage crossbar(s) 232). In this way, the master controller mayidentify center stage crossbar(s) 232 and center stage device(s) 230which, though operating independently from one another, together serveas the center stage of switch 200.

As further shown in FIG. 3, process 300 may include providing, from themaster controller, control information, associated with forwarding data,to the sending outer stage device, to center stage devices, and to areceiving outer stage device (block 340). For example, the mastercontroller may send control information to crossbar controller(s) 228 ofall or some of outer stage device(s) 220 of switch 200 (e.g., to outerstage device(s) 220 connected to sending network device 210 and/or to areceiving network device(s) 210). The control information may includeinformation associated with controlling an outer stage crossbar 226 ofouter stage device 220. For example, the control information may includeinstructions (e.g., a routing table and/or forwarding table) used bycrossbar controller 228 to interconnect input cross-point(s) with outputcross-point(s) of outer stage crossbar 226. In some implementations, thecontrol information may include information associated with controllingoperations performed by port controller 224 (e.g., encapsulation,decapsulation, segmentation, concatenation, or the like).

Additionally, or alternatively, the master controller may send controlinformation to crossbar controller(s) 234 of all or some center stagedevice(s) 230 of switch 200 (e.g., to particular center stage device(s)230 via which outer stage device(s) 220 are to forward data from sendingnetwork device 210 and receiving network device(s) 210). The controlinformation may include information associated with controlling centerstage crossbar(s) 232 of center stage device(s) 230. For example, thecontrol information may include instructions (e.g., a routing tableand/or forwarding table) used by crossbar controller 234 to interconnectinput cross-point(s) with output cross-point(s) of center stage crossbar232. In this way, the master controller may distribute controlinformation associated with controlling devices of switch 200, tocontrollers associated with the devices of switch 200 without requiringthe exchange of control information between center stage device(s) 230or center stage crossbar(s) 232.

As further shown in FIG. 3, process 300 may include forwarding the data,from the sending outer stage device to the center stage devices, basedon control information received from the master controller (block 350).For example, in some implementations, crossbar controller 228 of outerstage device 220 may determine, based on the control information,operations to be performed by port controller 224. Crossbar controller228 may likewise control port controller 224 to perform thoseoperations. Crossbar controller 228 may determine, based on the controlinformation, interconnections to be made between particular inputcross-point(s) (e.g., corresponding to port(s) 222 to which sendingnetwork device 210 is connected) and particular output cross-points(e.g., corresponding to data planes of switch 200's center stage) of aningress stage of outer stage crossbar 226. Crossbar controller 228 maylikewise control outer stage crossbar 226 to make thoseinterconnections.

Port controller 224 may perform operations on the data received viaport(s) 222 and may provide the data to the particular inputcross-point(s), of the ingress stage, whereby the data may be forwardedfrom the particular output cross-point(s) to center stage device(s) 230connected to the particular output cross-point(s) via link(s) 240.Likewise, center stage crossbar(s) 232, of center stage device(s) 230,may receive, via input cross-point(s) corresponding to the particularoutput cross-point(s) of the ingress stage, the data sent from outerstage device 220. In this way, switch 200 may forward data from aningress stage, of an outer stage device 220 connected to a sendingnetwork device 210, to a center stage formed by one or more independentcenter stage crossbars 234 of center stage device(s) 230.

As further shown in FIG. 3, process 300 may include forwarding the data,from the center stage devices to the receiving outer stage device, basedon the control information received from the master controller (block360). For example, a crossbar controller 234, associated with aparticular center stage crossbar 232, of center stage device 230, towhich outer stage device 220 sends the data, may determine, based on thecontrol information, interconnection(s) to be made between a particularinput cross-point (e.g., associated with link(s) 240 via which centerstage device 230 receives the data from a particular sending outer stagedevice 220) and particular output cross-point(s) (e.g., associated withlink(s) 240 via which center stage device 230 sends the data to aparticular receiving outer stage device 220) of a center stage of centerstage crossbar 232. Crossbar controller 234 may likewise direct centerstage crossbar 323 to make those interconnections such that center stagecrossbar 230 forwards the data received from the sending outer stagedevice 220, via the particular input cross-point and correspondinglink(s) 240, to the receiving outer stage device(s) 220, via theparticular output cross-point(s) and corresponding link(s) 240. In thisway, switch 200 may forward data from the center stage, formed by one ormore independent center stage crossbars 234 of center stage device(s)234, to an egress stage, of an outer stage device 220 connected to areceiving network device 210.

As further shown in FIG. 3, process 300 may include sending, to areceiving network device, the data via a port of the receiving outerstage device (block 370). For example, crossbar controller 228 ofreceiving outer stage device 220 may determine, based on controlinformation (e.g., stored by receiving outer stage device 220 and/orreceived from the master controller), interconnections to be madebetween particular input cross-points (e.g., corresponding to dataplanes of switch 200's center stage) and particular output cross-points(e.g., corresponding to port(s) 222 to which receiving network device(s)210 are connected) of an egress stage of outer stage crossbar 226.Crossbar controller 228 may likewise control outer stage crossbar 226 tomake those interconnections. In some implementations, crossbarcontroller 228 may determine, based on the control information,operations to be performed by port controller 224.

Outer stage crossbar 226, of receiving outer stage device 220, mayreceive, via the particular input cross-point(s), the data sent fromcenter stage device(s) 230 to thereby provide the data to receivingnetwork device(s) 210 connected to egress port(s) 222 associated withthe particular output cross-point(s). In some implementations, crossbarcontroller 228 may control port controller 224 to perform operationsbased on the configuration information. In this way, switch 200 mayforward data from an egress stage, of an outer stage device 220, toport(s) 222 connected to receiving network device(s) 210.

Although FIG. 3 shows example blocks of process 300, in someimplementations, process 300 may include additional blocks, fewerblocks, different blocks, or differently arranged blocks than thosedepicted in FIG. 3. Additionally, or alternatively, two or more of theblocks of process 300 may be performed in parallel.

FIGS. 4A-4G are diagrams of an example implementation 400 relating tothe example process 300 shown in FIG. 3. FIGS. 4A-4G show examples offorwarding data using a multi-chassis network switch having one or moreindependent modular center stage devices.

As shown in FIG. 4A, assume, for example implementation 400, that asender (e.g., a network device 210) sends a packet to a port P-1 (e.g.,a port 222) of a sending LCC (e.g., an outer stage device 220). Assumefurther that the packet includes a data payload and control information,associated with forwarding the packet, which identifies the packet as“Packet,” having “sender” as a source and “receiver” as a destination.

As shown in FIG. 4B, assume, for example implementation 400, that a portcontroller (e.g., port controller 224), associated with port P-1 of thesending LCC, identifies the control information associated withforwarding the packet and supplements the control information toidentify a source port of the packet (e.g., port P-1). Assume furtherthat the port controller provides the supplemented control informationto a crossbar controller (e.g., a crossbar controller 228), of thesending LCC, which updates previously stored control information (e.g.,a forwarding table) based on the supplemented control information.Assume further that the crossbar controller provides the supplementedcontrol information to a master crossbar controller (e.g., a crossbarcontroller 228 of another outer stage device 220, shown as “Master LCC”)to enable the master crossbar controller to update the master crossbarcontroller's stored control information.

As shown in FIG. 4C, assume, for example implementation 400, that afirst fabric card, including a center stage crossbar (e.g., a centerstage crossbar 232) and a corresponding crossbar controller (e.g., acrossbar controller 234), is installed in a center stage chassis (e.g.,a center stage device 230). Assume further that the crossbar controllersends control information, associated with the center stage crossbar, tothe master crossbar. The control information identifies the first fabriccard as the device, the center stage crossbar as the crossbar, andconnections between the center stage crossbar's input/outputcross-points and cross-points of other devices. Assume that the controlinformation indicates that input cross-point CI-1 is connected to outputcross-point IO-1 of the sending LCC's ingress stage crossbar. Assumethat the control information further indicates that output cross-pointCO-2 is connected to input cross-point EI-1 of a receiving LCC's egresscrossbar (e.g., an egress stage of an outer stage crossbar 226 of anouter stage device 220).

Assume that the master crossbar controller receives the controlinformation from the crossbar controller and updates control informationstored by the master crossbar controller. Based on the updated controlinformation, the master crossbar controller determines that the receiveris connected to a port of the receiving LCC and sends controlinformation to the first fabric card's crossbar controller. The controlinformation indicates that the first fabric card's center stage crossbaris to interconnect input cross-point CI-1 and output cross-point CO-2 toforward “Data Segment (1)” to input cross-point EI-1 of the receivingLCC's egress crossbar.

Assume that a second fabric card is also installed in the center stagechassis. Assume further that the second fabric card's crossbarcontroller similarly exchanges control information with the mastercrossbar controller. The master crossbar controller thus receives, fromthe second fabric card's crossbar controller, control informationindicating that input cross-point CI-1 is connected to outputcross-point IO-2 of the sending LCC's ingress stage crossbar and thatoutput cross-point CO-2 is connected to input cross-point EI-2 of areceiving LCC's egress crossbar. Likewise, the master crossbarcontroller sends, to the crossbar controller of the second fabric card,control information indicating that the first fabric card's center stagecrossbar is to interconnect input cross-point CI-1 and outputcross-point CO-2 to forward “Data Segment (2)” to input cross-point EI-2of the receiving LCC's egress crossbar.

As shown in FIG. 4D, assume, for example implementation 400, that themaster crossbar controller sends, to the crossbar controller of thesending LCC, control information indicating that the port controller isto segment “Packet” into “Data Segment (1)” and “Data Segment (2)” andthe ingress crossbar to interconnect input cross-point II-1 with outputcross-points IO-1 and IO-2 to forward “Data Segment (1)” and “DataSegment (2),” respectively. Assume further that the master crossbarcontroller sends, to a crossbar controller of a receiving LCC, controlinformation indicating that the egress crossbar is to interconnect inputcross-points EI-1 and EI-2 with output cross-point EO-2 to forward “DataSegment (1)” and “Data Segment (2),” respectively, and that the portcontroller is to combine “Data Segment (1)” and “Data Segment (2)” into“Packet.”

As shown in FIG. 4E, assume, for example implementation 400, that thecrossbar controller of the sending LCC controls, based on the controlinformation received from the master crossbar controller, the portcontroller to segment “Packet” into “Data Segment (1)” and “Data Segment(2)” and provide each segment to input cross-point II-1 of the ingresscrossbar. Assume further that the crossbar controller of the sending LCCcontrols, based on the control information received from the mastercrossbar controller, the ingress crossbar to interconnect inputcross-point II-1 with output cross-point IO-1 to forward “Data Segment(1)” to the center stage crossbar of the first fabric card and tointerconnect input cross-point II-1 with output cross-point IO-2 toforward “Data Segment (2)” to the center stage crossbar of the secondfabric card.

As shown in FIG. 4F, assume, for example implementation 400, that thecrossbar controller of the first fabric card controls, based on thecontrol information received from the master crossbar controller, thecenter stage crossbar to interconnect input cross-point CI-1 with outputcross-point CO-2 to forward “Data Segment (1)” from output cross-pointIO-1 of the sending LCC's ingress crossbar to input cross-point EI-1 ofthe receiving LCC's egress crossbar. Likewise, the crossbar controllerof the second fabric card controls, based on the control informationreceived from the master crossbar controller, the center stage crossbarto interconnect input cross-point CI-1 with output cross-point CO-2 toforward “Data Segment (2)” from output cross-point IO-2 of the sendingLCC's ingress crossbar to input cross-point EI-2 of the receiving LCC'segress crossbar.

As shown in FIG. 4G, assume, for example implementation 400, that thecrossbar controller of the receiving LCC controls, based on the controlinformation received from the master crossbar controller, the egresscrossbar to interconnect input cross-point EI-1 with output cross-pointEO-2 to forward “Data Segment (1)” from the center stage crossbar of thefirst fabric card to the port controller and to interconnect inputcross-point EI-2 with output cross-point EO-2 to forward “Data Segment(2)” from the center stage crossbar of the second fabric card to theport controller. Assume further that the crossbar controller of thesending LCC controls, based on the control information received from themaster crossbar controller, the port controller to combine “Data Segment(1)” and “Data Segment (2)” into “Packet” and provide “Packet” to a portP-2 of the receiving LCC. A receiver (e.g., a network device 210),connected to port P-2, may thus receive “Packet.”

In this way, a multi-chassis network switch may be implemented toforward data from one device to another through independent center stagedevices.

As indicated above, FIGS. 4A-4G are provided merely as examples. Otherexamples are possible and may differ from what was described with regardto FIGS. 4A-4G.

FIGS. 5A-5D are diagrams of example implementations 500-530 relating toexample process 300 shown in FIG. 3. FIGS. 5A-5D show examples offorwarding data using a multi-chassis network switch having one or moreindependent modular center stage devices.

As shown in FIG. 5A, assume, for example implementation 500, that amulti-chassis switch (e.g., switch 200) includes first and second LCC(e.g., outer stage devices 220) as well as first, second, and thirdcenter stage chassis (e.g., center stage devices 230). Assume furtherthat each LCC includes ingress and egress crossbars (e.g., an outerstage crossbar 226) and a crossbar controller (e.g., crossbar controller228), and each center stage chassis includes a pair of fabric cards,each having a center stage crossbar (e.g., center stage crossbar 232)and a crossbar controller (e.g., crossbar controller 234). Input andoutput cross-points of each LCC's ingress and egress crossbars areconnected (e.g., via links 240) to corresponding output and inputcross-points of each fabric cards' center stage crossbars. Likewise, thecrossbar controllers of the switch are connected to the first LCC'scrossbar controller, which serves as the master crossbar controller ofthe switch. Thus, the first LCC's crossbar controller may control theswitch's other crossbar controllers to forward data between devicesconnected to the ports of the first and second LCC through the fabriccards' center stage crossbars.

As shown in FIG. 5B, assume, for example implementation 510, that anetwork operator adds, to the switch of example implementation 500, athird LCC (e.g., another outer stage device 220). Assume further thatthe network operator adds two additional stage chassis, each containingfour fabric cards, and installs third and fourth fabric cards into eachof the other center stage chassis. Assume further that the networkoperator makes additional connections (e.g., via links 240) between thedevices of the switch such that input and output cross-points of eachLCC's ingress and egress crossbars are connected to corresponding outputand input cross-points of each fabric cards' center stage crossbars.Likewise, the network operator connects the crossbar controllers, of theadditional LCC and fabric cards, to the first LCC's crossbar controller,which serves as the master crossbar controller of the switch. In thisway, the network operator may upgrade the switch by adding outer stagedevices, by adding center stage devices, and/or by providing additionalcenter stage crossbars (and associated controllers) to existing centerstage devices.

As shown in FIG. 5C, assume, for example implementation 520, that thefirst LCC of example implementation 510 experiences a failure, is takenoffline, or is otherwise rendered unusable. One or more of the remainingcrossbar controllers may detect the failure (e.g., by receiving controlinformation indicating that the first LCC has become unusable and/or byfailing to receive control information indicating that the first LCCremains usable) and may select the crossbar controller of another LCC(e.g., the second LCC) to become the master crossbar controller (e.g.,by an election, ranking, and/or manual selection process). In this way,the switch may continue operating despite the failure of a mastercrossbar controller and limit network interruptions associated with aparticular offline outer stage device to only devices connected to portsof the particular offline outer stage device.

As shown in FIG. 5D, assume, for example implementation 530, that thefirst center stage chassis, and the fabric cards therein, of exampleimplementation 510 experiences a failure, is taken offline, or isotherwise rendered unusable. The master crossbar controller of the firstLCC may detect the failure (e.g., by receiving control informationindicating that the first center stage chassis has become unusableand/or by failing to receive control information indicating that thefirst center stage chassis remains usable). Likewise, the mastercontroller may provide control information to the other LCC crossbarcontrollers directing the ingress and egress crossbars of the LCC toforward data through the remaining fabric cards of the remaining centerstage chassis. In this way, the switch may continue operating, withoutnetwork downtime, despite the loss of one or more center stage crossbarsand/or center stage devices.

As indicated above, FIGS. 5A-5D are provided merely as examples. Otherexamples are possible and may differ from what was described with regardto FIGS. 5A-5D.

Implementations described herein may assist a network operator inoperating a multi-chassis switch by using one or more modular centerstage chassis configured to meet physical and/or operationalrequirements. Independently operated modular center stage chassis mayfurther assist the network operator in implementing and scaling themulti-chassis switch while enabling the switch to continue operatingdespite a failure of one or more components.

The foregoing disclosure provides illustration and description, but isnot intended to be exhaustive or to limit the implementations to theprecise form disclosed. Modifications and variations are possible inlight of the above disclosure or may be acquired from practice of theimplementations.

As used herein, the term component is intended to be broadly construedas hardware, firmware, and/or a combination of hardware and software.

As used herein, a packet may refer to a network packet, a frame, adatagram, a segment, a fragment of a packet, a fragment of a frame, afragment of a datagram, a fragment of a segment, or any other formattedor unformatted unit of data capable of being transmitted via a network.

It will be apparent that systems and/or methods, described herein, maybe implemented in different forms of hardware, firmware, or acombination of hardware and software. The actual specialized controlhardware or software code used to implement these systems and/or methodsis not limiting of the implementations. Thus, the operation and behaviorof the systems and/or methods were described herein without reference tospecific software code—it being understood that software and hardwarecan be designed to implement the systems and/or methods based on thedescription herein.

Even though particular combinations of features are recited in theclaims and/or disclosed in the specification, these combinations are notintended to limit the disclosure of possible implementations. In fact,many of these features may be combined in ways not specifically recitedin the claims and/or disclosed in the specification. Although eachdependent claim listed below may directly depend on only one claim, thedisclosure of possible implementations includes each dependent claim incombination with every other claim in the claim set.

Some implementations are described herein in connection with thresholds.As used herein, satisfying a threshold may refer to a value beinggreater than the threshold, more than the threshold, higher than thethreshold, greater than or equal to the threshold, less than thethreshold, fewer than the threshold, lower than the threshold, less thanor equal to the threshold, equal to the threshold, etc.

No element, act, or instruction used herein should be construed ascritical or essential unless explicitly described as such. Also, as usedherein, the articles “a” and “an” are intended to include one or moreitems, and may be used interchangeably with “one or more.” Furthermore,as used herein, the term “set” is intended to include one or more items,and may be used interchangeably with “one or more.” Where only one itemis intended, the term “one” or similar language is used. Also, as usedherein, the terms “has,” “have,” “having,” or the like are intended tobe open-ended terms. Further, the phrase “based on” is intended to mean“based, at least in part, on” unless explicitly stated otherwise.

What is claimed is:
 1. A system comprising: a first device, the firstdevice being associated with an ingress stage and an egress stage of aswitch fabric, the first device including: a first crossbar, associatedwith the switch fabric, comprising: a first crossbar componentassociated with the ingress stage, and a second crossbar componentassociated with the egress stage; a second device, the second devicebeing associated with a center stage of the switch fabric, the seconddevice including: a second crossbar, associated with the switch fabric,comprising: a third crossbar component associated with the center stage;a third crossbar, associated with the switch fabric, comprising: afourth crossbar component associated with the center stage,  the thirdcrossbar component connecting, via one or more data links, to the firstcrossbar component and to the second crossbar component but not to thethird crossbar, and  the fourth crossbar component connecting, via theone or more data links, to the first crossbar component and to thesecond crossbar component but not to the second crossbar; a firstcontroller, the first controller connecting, via one or more controllinks, to the first crossbar; a second controller, the second controllerconnecting, via the one or more control links, to the second crossbarand to the first controller but not to the third crossbar; and a thirdcontroller, the third controller connecting, via the one or more controllinks, to the third crossbar and to the first controller but not to thesecond crossbar.
 2. The system of claim 1, further comprising: a firstchassis to house one or more devices, the first chassis housing thefirst device; and a second chassis to house one or more devices, thesecond chassis housing the second crossbar, and the second chassis beingseparate from the first chassis.
 3. The system of claim 2, the secondchassis housing the third crossbar.
 4. The system of claim 2, furthercomprising: a third chassis to house one or more devices, the thirdchassis housing the third crossbar, and the third chassis being separatefrom the first chassis and the second chassis.
 5. The system of claim 1,further comprising: a third device, the third device being associatedwith the ingress stage and the egress stage of the switch fabric, thethird device including: a fourth crossbar, associated with the switchfabric, comprising: a fifth crossbar component associated with theingress stage,  the fifth crossbar component connecting to the thirdcrossbar component and the fourth crossbar component, and  a sixthcrossbar component associated with the egress stage, the sixth crossbarcomponent connecting, via the one or more data links, to the thirdcrossbar component and the fourth crossbar component; and a fourthcontroller, the fourth controller connecting, via the one or morecontrol links, to the first controller.
 6. The system of claim 1,further comprising: a third device, the third device being associatedwith the center stage of the switch fabric, the third device including:a fourth crossbar, associated with the switch fabric, comprising: afifth crossbar component associated with the center stage,  the fifthcrossbar component connecting, via the one or more data links, to thefirst crossbar component and to the second crossbar component but not tothe second crossbar or to the third crossbar; and a fourth controller,the fourth controller connecting, via the one or more control links, tothe fourth crossbar and to the first controller but not to the secondcrossbar or to the third crossbar.
 7. The system of claim 1, the one ormore control links further comprising: a first subset of control links;and a second subset of control links, the first subset being separatefrom the second subset, the first subset connecting the secondcontroller to the second crossbar and to the first controller, and thesecond subset connecting the third controller to the third crossbar andto the first controller.
 8. A system comprising: a first switchingcomponent, being installed in a first chassis, to receive data from asending device, the data being intended for a receiving device; a firstcontroller, installed in the first chassis, to: obtain first controlinformation associated with forwarding the data, identify, based on thefirst control information, a second switching component and a thirdswitching component, the second switching component being installed in asecond chassis, and the third switching component being installed in athird chassis, and control the first switching component to provide afirst portion of the data, provided by the sending device, to the secondswitching component and a second portion of the data, provided by thesending device, to the third switching component; a second controller,separate from the first controller, to: obtain, from a mastercontroller, second control information associated with forwarding thedata, identify, based on the second control information, a fourthswitching component connected to the receiving device, the fourthswitching component not being installed in the second chassis, andcontrol, based on the second control information, the second switchingcomponent to forward the first portion of the data to the fourthswitching device; a third controller, separate from the first controllerand independent of the second controller, to: obtain, from a mastercontroller, third control information associated with forwarding thedata, identify, based on the third control information, the fourthswitching component connected to the receiving device, the fourthswitching component not being installed in the third chassis, andcontrol, based on the third control information, the third switchingcomponent to forward the second portion of the data to the fourthswitching device.
 9. The system of claim 8, further comprising: a fourthcontroller, separate from the first controller, the second controller,and the third controller, to: control the fourth switching component toprovide the first portion of the data, provided by the second switchingcomponent, and the second portion of the data, provided by the thirdswitching component, to the receiving device, the fourth controllerbeing installed in a fourth chassis.
 10. The system of claim 9, wherethe first controller is the master controller, the first controllerbeing further to: provide, to the fourth controller, fourth controlinformation identifying a connection between the first switchingcomponent and the sending device.
 11. The system of claim 9, where thefourth controller is the master controller, the first controller beingfurther to: provide, to the fourth controller, fourth controlinformation based on receiving the data from the sending device; thefourth controller being further to: provide the second controlinformation, to the second controller, based on receiving the fourthcontrol information, and provide the third control information, to thethird controller, based on receiving the fourth control information. 12.The system of claim 9, the second switching component connecting, via afirst group of links between the second chassis and each of the firstchassis and the fourth chassis, to the first switching component and tothe fourth switching component; and the third switching componentconnecting, via a second group of links between the third chassis andeach of the first chassis and the fourth chassis, to the first switchingcomponent and to the fourth switching component, the second group oflinks being separate from the first group of links.
 13. The system ofclaim 8, the master controller connecting, via control links, to thefirst controller, the second controller, and the third controller, thesecond controller not being connected, via the control links, to thethird controller.
 14. The system of claim 8, where each of the secondswitching component and the third switching component are a crossbarswitch.
 15. A system comprising: a chassis; a first group of switches,installed within the chassis, each switch, of the first group ofswitches, including: a first group of inputs, and a first group ofoutputs; a first group of controllers, associated with the first groupof switches, installed within the chassis, each controller, of the firstgroup of controllers, being independent of any other controller, of thefirst group of controllers, and each controller, of the first group ofcontrollers, corresponding to a switch, of the first group of switches,to selectively control the switch to connect inputs, of the first groupof inputs, with outputs, of the first group of outputs; a second groupof switches, including: a second group of inputs and a second group ofoutputs, the first group of inputs connecting, via a group of datalinks, to the second group of outputs, and the first group of outputsconnecting, via the group of data links, to the second group of inputs;and a second group of controllers associated with the second group ofswitches, the second group of controllers to: control the second groupof switches to selectively connect inputs, of the second group ofinputs, to outputs, of the second group of outputs, and control thefirst group of controllers, the second group of controllers connecting,via a group of control links, to the first group of controllers.
 16. Thesystem of claim 15, further comprising: another chassis separate fromthe chassis, the second group of switches and the second group ofcontrollers being installed within the other chassis, the chassisconnecting, via the group of data links, to the other chassis, and thechassis connecting, via the group of control links, to the otherchassis.
 17. The system of claim 15, further comprising: another chassisseparate from the chassis; a third group of switches installed withinthe other chassis, each switch, of the third group of switches,including: a third group of inputs, the third group of inputsconnecting, via another group of data links, to the second group ofoutputs, and a third group of outputs, the third group of outputsconnecting, via the other group of data links, to the second group ofinputs; and a third group of controllers, associated with the thirdgroup of switches, installed within the other chassis, the third groupof controllers connecting, via another group of control links, to firstgroup of controllers, each controller, of the third group ofcontrollers, being independent of any other controller of the firstgroup of controllers and any other controller of the third group ofcontrollers, and each controller, of the third group of controllers,corresponding to a switch, of the third group of switches, toselectively control the switch to connect inputs, of the third group ofinputs, with outputs, of the third group of outputs.
 18. The system ofclaim 15, where the second group of controllers further comprises amaster controller, each of the controllers, of the first group ofcontrollers, connecting, via the group of control links, to the mastercontroller.
 19. The system of claim 18, the master controller furtherconnecting, via the group of control links, to each of the othercontrollers of the second group of controllers.
 20. The system of claim15, where the data links comprise optical fiber.